John McCain took to the Senate floor on Wednesday to repudiate suggestions by his fellow Republican lawmaker, Michele Bachmann, that the family of a longtime aide to secretary of state Hillary Clinton had ties to Egypt's Muslim Brotherhood.

McCain praised the work and patriotism of Huma Abedin, a State Department employee who has been a constant presence at Clinton's side. Without mentioning congresswoman Bachmann by name, McCain described the attacks on Abedin, a Muslim, as an example of ignorance and fear that defames the spirit of the nation.

"Huma represents what is best about America: the daughter of immigrants, who has risen to the highest levels of our government on the basis of her substantial personal merit and her abiding commitment to the American ideals that she embodies so fully." McCain said. "I am proud to know Huma and to call her my friend."

Bachmann, a member of the House intelligence committee, made the allegations in a June letter to the state department as well as in a letter Wednesday to fellow Minnesota lawmaker, represenative Keith Ellison, a Democrat.

Bachmann said Abedin's late father, mother and brother are connected to Muslim Brotherhood operatives and/or organizations. She cited foreign media reports and an outside study and added that Abedin's position "affords her routine access to the secretary and policy-making".

In her letter to Ellison, Bachmann wrote, "Given what we know from the international media about Ms Abedin's documented family connections with the extremist Muslim Brotherhood," how was she not disqualified for a US security clearance.

McCain pointed out that Abedin's father died two decades ago and that the congresswoman failed to provide "one instance of an action, decision or a public position that Huma has taken while at the State Department that would lend credence to the charge that she is promoting anti-American activities within our government".

Clinton recently traveled to Egypt and urged president Mohamed Morsi of the Muslim Brotherhood and field marshal Hussein Tantawi of the military to work together. The two are in a power struggle.

In his letter to Bachmann, Ellison said the congresswoman, who was a candidate for the Republican presidential nomination, provided no information to substantiate her claims about Abedin. Ellison also is a Muslim.

McCain, who described himself as someone who understands the pain "when a person's character, reputation and patriotism are attacked", criticized Bachmann's actions.

"When anyone, not least a member of Congress, launches specious and degrading attacks against fellow Americans on the basis of nothing more than fear of who they are and ignorance of what they stand for, it defames the spirit of our nation, and we all grow poorer because of it," he said.

Abedin worked for Clinton when Clinton served as a US senator representing New York and sought the Democratic presidential nomination in 2008. Abedin is married to former representative Anthony Weiner of New York.

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